This invention relates to an internal combustion engine and more particularly to an improved cylinder head construction for such engines.
As is well known, internal combustion engines whether they are four or two cycle type generally are comprised of three major external engine bodies. These include the cylinder head body, the cylinder block body, and the crankcase body. Sometimes these bodies are combined and other times parts of each body may be formed from a part of the adjacent body. For the most part, however, each body is a separate element and is detachably or otherwise connected to the remaining bodies.
This presents significant problems with connection with the cylinder head design, particularly where the engine is of the four cycle type and has overhead valves and a valve actuating mechanism that is mounted in the cylinder head for operating these valves. It is quite difficult to provide a single piece assembly that will serve all of the purposes and which can be made in mass production quantities at a relatively low cost and still have high accuracy.
For example, motorcycle engines may at times utilize overhead valves that are operated by one or more cam shafts positioned in the crankcase or at a lower portion of the engine and operated via push rods and rocker arms. With such an arrangement, the cylinder head must form the combustion chamber surface, the intake and exhaust passages and valve seats for gas exchange with the combustion chamber, the mounting for the valves for controlling the flow through these passages and the actuating mechanisms for operating these valves. Furthermore, the actuating mechanism is frequently contained within a cover so as to protect the mechanism and particularly permit its lubrication without encroachment of foreign material into the mechanism while permitting ease of access for servicing.
Thus, many times the engine cylinder head is comprised of a main cylinder head member and a cam or valve cover that covers the outer periphery of the cylinder head member. However, this still gives rise to certain problems in connection with mounting all of the various components and arranging them in the cylinder head.
It is, therefore, a principal object of this invention to provide an improved cylinder head assembly for an overhead valve engine wherein the cylinder head is made up of a few major parts that are detachably connected to each other so as to facilitate production, maintain close tolerances and still keep the cost low.
It is a further object of this invention to provide an improved and simplified multi-piece cylinder head assembly for an overhead valve engine.
As has been noted, serviceability as well as assembly are important in the design. This is particularly true with respect to the cylinder head assembly. Its components are among those which require periodic adjustment or other servicing.
It is, therefore, a still further object of this invention to provide an improved and simplified cylinder head assembly of multi-piece construction to facilitate assembly as well as servicing.